/*
 * Copyright (c) 2013. wyouflf (wyouflf@gmail.com)
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.dongfang.net.http.client.multipart;

import com.dongfang.net.http.client.multipart.content.ContentBody;

/**
 * FormBodyPart class represents a content body that can be used as a part of multipart encoded entities. This class
 * automatically populates the header with standard fields based on the content description of the enclosed body.
 * 
 * @since 4.0
 */
public class FormBodyPart {

	private final String name;
	private final MinimalFieldHeader header;

	private final ContentBody body;

	public FormBodyPart(final String name, final ContentBody body) {
		super();
		if (name == null) {
			throw new IllegalArgumentException("Name may not be null");
		}
		if (body == null) {
			throw new IllegalArgumentException("Body may not be null");
		}
		this.name = name;
		this.body = body;
		this.header = new MinimalFieldHeader();

		generateContentDisposition(body);
		generateContentType(body);
		generateTransferEncoding(body);
	}

	public FormBodyPart(final String name, final ContentBody body, final String contentDisposition) {
		super();
		if (name == null) {
			throw new IllegalArgumentException("Name may not be null");
		}
		if (body == null) {
			throw new IllegalArgumentException("Body may not be null");
		}
		this.name = name;
		this.body = body;
		this.header = new MinimalFieldHeader();

		if (contentDisposition != null) {
			addField(MIME.CONTENT_DISPOSITION, contentDisposition);
		}
		else {
			generateContentDisposition(body);
		}
		generateContentType(body);
		generateTransferEncoding(body);
	}

	public String getName() {
		return this.name;
	}

	public ContentBody getBody() {
		return this.body;
	}

	public MinimalFieldHeader getHeader() {
		return this.header;
	}

	public void addField(final String name, final String value) {
		if (name == null) {
			throw new IllegalArgumentException("Field name may not be null");
		}
		this.header.addField(new MinimalField(name, value));
	}

	protected void generateContentDisposition(final ContentBody body) {
		StringBuilder buffer = new StringBuilder();
		buffer.append("form-data; name=\"");
		buffer.append(getName());
		buffer.append("\"");
		if (body.getFilename() != null) {
			buffer.append("; filename=\"");
			buffer.append(body.getFilename());
			buffer.append("\"");
		}
		addField(MIME.CONTENT_DISPOSITION, buffer.toString());
	}

	protected void generateContentType(final ContentBody body) {
		StringBuilder buffer = new StringBuilder();
		buffer.append(body.getMimeType()); // MimeType cannot be null
		if (body.getCharset() != null) { // charset may legitimately be null
			buffer.append("; charset=");
			buffer.append(body.getCharset());
		}
		addField(MIME.CONTENT_TYPE, buffer.toString());
	}

	protected void generateTransferEncoding(final ContentBody body) {
		addField(MIME.CONTENT_TRANSFER_ENC, body.getTransferEncoding()); // TE cannot be null
	}

}
